Photographic silver halide emulsions sensitized with thioether and developer combinations



United States Patent N0 Drawing. Fiied Aug. 17, 1961, Ser. No. 132,011

15 Claims. (Cl. 96-95) This invention concerns photographic silver halide emulsions, and more particularly, photographic silver halide emulsions containing novel combinations of sensitizing addenda.

It is well known in the photographic art that silver halide emulsions can be chemically sensitized with a variety of materials in order to increase their speed. Certain chemical sensitizers are believed to react with the silver halide to form on the surface of the silver halide minute amounts of silver sulfide, or of silver, or of other noble metals. In addition, other classes of compounds that apparently do not enter into chemical combination with the silver halide can be utilized to increase the sensitivity of photographic silver halide emulsions. Such sensitization reaches a limit beyond which further addition of sensitizer merely increases the fog of the photographic emulsion with constant or decreasing speed.

It is an object of this invention to provide novel photographic silver halide emulsions that have increased sensitivity.

It is another object of the invention to provide photographic silver halide emulsions containing novel synergistic combinations of sensitizing materials.

It is still another object of this invention to substan tially increase the speed of photographic silver halide emulsions without increasing fog to objectionable levels. These and other objects of the'invention are accomplished by incorporating into photographic silver halide emulsions sensitizing amounts of a combination comprising: (1) a thioether silver halide chemical sensitizer, and (2) a photographic silver halide developing agent such as a hydroquinone developing agent with a compound capable of forming a bisulfite ion or a B-pyrazolidone developing agent or combinations of such developing agents.

A wide variety of 3-pyrazolidone silver halide developing agents can be utilized in the sensitizer combinations of the invention, a Wide variety of such developing agents being known in the art. Suitable 3-pyrazo1idone developing agents are disclosed in Kendall US. Patent 2,289,- I

367, issued July 14, 1942; Wilson U.S. Patent 2,685,516, issued August 3, 1954; Allen et al. US. Patent 2,772,- 282, issued November 27, 1956; Hood et al. US. Patent 2,751,297 issued June 19, 1956; and others. Typical 3- pyrazolidone developing agents have the formula wherein R can be hydrogen atoms, hydrocarbon radicals such as alkyl heterocyclic or aryl groups including phenyl, naphthyl and substituted hydrocarbon groups; and Wherein R R R and R can be hydrogen atoms, hydrocarbon radicals such as alkyl groups preferably containing 1 to 4 carbon atoms or aryl groups including phenyl, naphthyl and substituted hydrocarbon groups. However, a wide variety of other B-pyrazolidone silver halide developing agents can be utilized in the invention. a As used herein the term 2-pyrazolidone silver halide developa means Patented June 29, 1965 ing agent refers to all of such developing agents and substituted derivatives thereof. Typical 3-pyrazolidone silver halide developing agents that can be suitably utilized include:

l-phenyl-3-pyrazolidone, 1-p-tolyl-3-pyrazolidone, 5-phenyl-3-pyrazolidone, 5-methyl-3-pyrazolidone, 1-p-chlorophenyl-3-pyrazolidone, l-phenyl-S-phenyl-3pyrazolidone, l-m-tolyl-B-pyrazolidone, l-phenyl-5-methyl-3-pyrazolidone, l-p-tolyl-5-pheny1-3-pyrazolidone, 1-p-methoxyphenyl-3-pyrazolidone, 1-acetamidophenyl-3-pyrazolidone, 1-phenyl-2-acetyl-4,4-dimethyl-3-pyrazolidone, l-phenyl-4,4-dimethyl-3-pyrazolidone, 1-m-aminophenyl-4-methyl-4-propyl-3-pyrazolidone, 1-ochlorophenyl-4-methyl-4-ethyl-3-pyrazolidone, l-m-acetamidophenyl-4,4-diethyl-3-pyrazolidone, l- (p-fl-hydroxyethylphenyl) -4,4-dimethyl-3- pyrazolidone, l-p-hydroxyphenyl-4,4 dimethy1-3-pyrazolidone, l-p-methoxyphenyll,4-diethyl-3-pyrazolidone, l-p-tolyl-4,4-dimethyl-3-pyrazolidone, l-(7-hydroXy-2-naphthyl)-4-methyl-4-n-propy1-3- pyrazolidone, 1-p-diphenyl-4,4-dimethyl-3-pyrazolidone, l-(p-fi-hydroxyethylphenyl)-3-pyrazolidone, '1-o-tolyl-3-pyrazolidone, 1-o-tolyl-4,4-dimethyl-3 pyrazolidone, 1-benzothiazolyl-3-pyrazolidone and others.

A diversity of hydroquinone silver halide developing agents with compounds capable of releasing or forming bisulfite ions can be utilized in the'present sensitizer combinations. Hydroquinone or substituted hydroquinones including alkyl-substituted hydroquinones, aryl-substitutedhydroquinones and other hydrocarbon-substituted hydroquinones, carboxyl-substituted hydroquinones, acylsubstituted hydroquinone, acyloxy-substituted hydroqinones, 'alkoXy-substituted hydroquinones, such as ptoluhydroquinone, 2,5-dihydroxybenzoic acid, and others can be used. The substituents on the hydroquinone generally have 1 to 20 and more generally 1 to 6 carbon atoms. A particularly useful class of compounds that release bisulfite ions are alkali metal bisulfites such as sodium bisulfite and potassium bisulfite. Other suitable bisulfite ion-producing compounds inclde sodim sulfite and potassium sulfite. Sulfur dioxide also can be utilized as a source of bisulfite ions. Sulfur dioxide and hydroquinones form clathrates, and thesulfur dioxide and hydroquinone are preferably added to the emulsion in this form. Such clathrates weredescribed by Mandelcorn in Chemical Reviews, 59, p. 827-830, October 1959. The bisulfite forming compound usually comprises less than one-half by weight of the combined weight of the hydroquinone and the bisulfite releasing compound, although larger amounts of bisulfite can be utilized. Preferably, at least about 5 molar percent of bisulfite ion based on the hydroquinone is utilized. For optimum results, the hydroquinone and the compound capable of releasing or forming a bisulfite ion are admixed or com.- bined prior to incorporation into photographic emulsions, although these compounds can be individually added to the emulsion.

Also, a wide variety of thioether silver halide chemical sensitizers can be utilized in the sensitizer combinations of the invention. A particularly useful group of thioethers are described in Dann and Chechak application U.S. Serial No. 779,874 filed December 12, 1958, now US. Patent No. 3,046,134. Reference is also made to Graham and Sagal application U.S. Serial No. 779,839, filed December 12, 1958, now US. Patent No. 3,046,129, wherein is described the use of the Dann and Chechak thioether sensitizers in silver halide emulsions containing color couplers. The useful Dann and Chechak sensitizers are linear polymers consisting essentially of repetitive units, each of which contains at least one thioether atom, and which have average molecular weights of at least about 250 and generally from 250 to 10,000, although polymers of 500 to 3500 have been found particularly useful. The Dann and Chechak sensitizers can be represented by the formula:

Formula I {-R-Sh wherein R is an aliphatic radical and x represents a positive integer of at least 3. The terminal groups of such polymers are generally hydrogen atoms, halogen atoms, alkenyl groups (e.g., vinyl, allyl, etc.), carboxylic groups (e.g. carboxyl, carboxylic amide, carboxylic ester, such as carbomethoxyl, carbethoxyl, etc.), hydroxyl groups, mercapto groups (or salts thereof, e.g., sodium, potassium, etc.), or combinations of these.

The linear polymers represented by Formula I above, comprise a well-known class of polymeric materials. Typical of the polymers embraced by Formula I are those polymers represented by the following general formula:

Formula II ER1 (XR 2) n-iS-R (X 1-R4) m1- S 1n wherein R R R and R each represents a hydrocarbon alkylene group containing from about 2 to 20 carbon atoms (e.g., ethylene, trimethylene, 1,2-propylene, tetrabutylene, pentamethylene, octamethylene, decamethylene, dodecamethylene, tetradecamethylene, etc.), X and X each represents an oxygen atom, a sulfur atom, an amino group (substituted or not) such as amino, methylamiuo, ethylamino, etc., carbamyl (NHCO), carbonylamido (CONH), carbonyl, oxyca-rbonyloxy, oxycarbonyl (OOC), carbonyloxy (COO), etc., provided that X does not represent an oxycarbonyl group when X represents a carbonyloxy group and X does not represent a carbamyl group when X represents a carbonylamido group, and p and In each represents a positive integer of from 1 to 5, and n represents the values given above, i.e., a positive integer of at least 3. An especially useful group of polymers represented by Formula II comprises the polymers represented by the following general formula:

Formula 111 wherein a, b, c and d each represents a positive integer of from 2 to 20, and n, m and p each have the values given above.

See Minsk application Serial No. 779,852, filed December 12, 1958, now US. Patent No. 3,046,133 for the photographic application of the polymers of Formula 11, wherein X represents an oxycarbonyl group when X represents a carbonyloxy group. See Beavers application Serial No. 779,875, filed December 12, 1958, now US. Patent No. 3,046,135 for the photographic application of the polymers of Formula II, wherein X represents a carbamyl group when X represents a carbonylamido group.

Another group of polymers embraced by Formula I above which are useful in our invention comprises the polymers represented by the following general formula:

Formula IV wherein R R X, n and p each have the values given above, X represents an oxygen atom or a sulfur atom, R

represents a hydrogen atom or a lower alkyl group (e.g., methyl, etc.), Z represents a divalent carbonamide linkage, e.g.,

wherein Z represents an alkylene group, such as that defined above for R or the group:

wherein R R and p each have the values given above, or alternatively, Z can represent an alkylene group such as wherein R represents an alkylene group, such as methylene, ethylene, trimethylene, 1,2-propylene, butylene, pentamethylene, hexamethylene, etc. Another group of polymers embraced by Formula I, which are useful in practicing our invention comprises polymeric linear lactones, such as:

Formula V 4R COOR -S-} wherein R R and it each have the values given above. Alternatively, the compounds of Formula V can be written as follows:

Formula Va wherein R R and n each have the values given above.

Another group of polymers embraced by Formula I are those represented by the following general formula:

Formula VI wherein R R R R X, X m, n and 2, each have the values given above and R represents a hydrogen atom, a lower alkyl group, such as methyl, ethyl, propyl, etc.

Still another group of polymers embraced by Formula I above are those represented by the following general formula:

In the above formulas, the symbol groups R R R R etc., and the integers in, n, p, etc., have the same values throughout.

The compounds of Formula II above can be prepared according to methods which have been previously described in the prior art. For example, these polymers can be prepared by condensing together at least one dihalogenated compound selected from those represented by the following general formula:

Formula. Ilia hal-R hal alent amount of at least one dithiol compound selected from those represented by the following general formula:

FormulaIIb HSR (X R SH The condensations can advantageously be carried out in the presence of an acid-binding material, such as sodium carbonate, pyridine, sodium acetate, etc. If desired, the

condensation can be carried out in the presence of an inert diluent which may be a solvent or non-solvent for the polymeric product obtained.

Alternatively, symmetrical polymers embraced by Formula II above can be prepared by condensing together an intermediate represented by Formula Ila with an alkali metal sulfide, such as sodium sulfide. Such preparations have been previously described in the prior art, such as Lilienfeld U.S. Patent 108,329, issued February 20, 1912.

The linear polymers represented by Formula IV above can advantageously be prepared by interacting at least one molecule of at least one compound selected from those represented by the followiing general formula:

with at least one molecule of at least one diolefinicallyunsaturated compound selected from those represented by the following general formula:

formula. IV!) H C=CH-ZCH=CH I This method has likewise been previously described in the prior art, such as Colfman U.S. Patent 2,347,182,- issued April 26, 1944.

The'linear polymers reprsented by Formula V above can advantageously be prepared by self-condensation of at least one hydroxy acid (or alternatively, a lactone of the acid) represented by the following general formula:

Formula Vb and two molecules of at least one alldehyde represented by the following general formula: 9

Formula V-Ib RQ(.7H with one molecule of at least one dithiol represented by the following general formula:

The condensations occur spontaneously on standing, although they can be accelerated by the application of heat, and in some instances, by the use of an inert diluent, such as ethanol, water, etc.

The linear polymers represented by Formula VII above can advantageously be prepared by condensing together two molecules of at least one amine selected from those represented by the following general formula:-

Formula VIIa R NH one molecule of at least one dithiol represented by the following general formula:

Formula. V'IIc O H-ii-lG-iJ-H These condensations also occur spontaneously on standing, but can be accelerated by the application of heat (e.g., 50150 (3.), use of solvents or dispersing agents, or other techniques well-known to those skilled in the art. Another useful group of thioether compounds that can be utilized in the present sensitizer combinations include cyclic thio ethers such as are represented by the formula:

\(R O) n R wherein n is an integer of at least 1 and generally 1 to 10 and R is an alkylene radical generally having 1 to 4 carbon atoms.

The present sensitizer addenda are added to the photographic emulsions in sensitizing amounts as determined by methods well known in the art. Generally, however, about .01 to 10 and preferably .1 to 5 grams of the thioether sensitizer, about .01 to 10 and preferably .1 to 5 grams of the 3-pyrazolidone developing agent, and about 1 to grams of the hydroquinone-bisulfite-forming com-' pound are utilized per mole of silver halide present in the emulsion. r

The subject sensitizer addenda can be incorporated directly into the photographic silver halide emulsion layer or, -alternatively, they can be utilized in contiguouslayers.

The preparation of photographic silver halide emulsions such as are used with the addenda of this invention involves three separate operations: (1) emulsification and digestion of silver halide, (2) the freeing of the emulsion of excess Water-soluble salts, suitably by washing with water, and (3) the second digestion or after-ripening to obtain increased emulsion speed or sensitivity. (Mees, The Theory of the Photographic Process, 1954.) The addenda of the invention can be added to the emulsion before the final digestion or after-ripening, or they can be added immediately prior to the coating.

The addenda of the invention can be added to photographic emulsions using any of the well-known techniques in emulsion making. For example, they can be dissolved in a suitable solvent and added to the silver halide emulsion, or they can be added to the emulsion in the form of a dispersion similar to the technique used toincorporate certain types of color-forming compounds (coupler's) in a photographic emulsion. Techniques of this type are described in Jelley et al. U.S. Patent 2,322,027, issued June 15, 1943, and Fierke et' al. US; Patent 2,801,171, issued July 30, 1957. The solvent should be selected so that it has no harmful effect upon the emulsion in accordance with usual practice, and generally solvents or diluents which are miscible with water are to be preferred.

The emulsions can be digested with naturally active gelatln, or sulfur compounds can be added, such as those described in Sheppard U.S. Patent 1,574,944, issued March. 2, 1926, and Sheppard et al. 1,623,499, issued April 5, 1927, and Sheppard and Brigham U.S. Patent 2,410,689, issued November 5, 1946. The emulsions can also be treated with salts of the noble metals such as ruthenium, rhodium, palladium, iridium and platinum. Representative compounds are ammonium chloropalladate, potassium chloroplatinate, and sodium chloropalladite, which are used in amounts below that which produces any substantial fog inhibition, as described in Smith and Trivelli 7 U.S. Patent 2,448,060, issued August 31, 1948, and as antifoggants in higher amounts, as described in Trivelli and Smith U.S. Patents 2,566,245, issued August 28, 1951, and 2,566,263, issued August 28, 1951. The emulsions can also contain small amounts of gold salts as described in Waller et al. U.S. Patent 2,399,083, issued April 23, 1946, or in Damschroder U.S. Patent 2,597,856, issued May 27, 1952, and Yutzy and Leermakers U.S. Patent 2,597,915, issued May 27, 1952. Suitable compounds are potassium chloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichloride, and 2-aurosulfobenzothiazole methochloride. The emulsions can also contain small amounts of reducing agents such as stannous salts (Carroll U.S. Patent 2,487,850, issued November 15, 1949), polyamines, such as diethylene triamine (Lowe and Jones U.S. Patent 2,518,698, issued August 15, 1950), polyamines, such as spermine (Lowe and Allen U.S. Patent 2,521,925, issued September 12, 1950), or bis(;3- aminoethyl) sulfide and its water-soluble salts (Lowe and Jones U.S. Patent 2,521,926, issued September 12, 1950).

The emulsions can also be optically sensitized with cyanine and merocyanine dyes, such as those described in Brooker U.S. Patents 1,846,301, issued February 23, 1932; 1,846,302, issued February 23, 1932; and 1,942,854, issued January 9, 1934; White U.S. Patent 1,990,507, issued February 12, 1935; Brooker and White U.S. Patents 2,112,140, issued March 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747, issued January 10, 1950; and 2,739,964, issued March 27, 1956; Brooker and Keyes U.S. Patent 2,493,748, issued January 10,1950; Sprague US. Patents 2,503,776, issued April 11, 1950 and 2,519,001, issued August 15, 1950; I-Ieseltine and Brooker U.S. Patent 2,666,761, issued January'19, 1954; Heseltine U.S. Patent 2,734,900, issued February 14, 1956; VanLare U.S. Patent 2,739,149, issued March 20, 1956; and Kodak Limited British Patent 450,958, accepted July 15, 1936.

The emulsions can contain a suitable gelatin plasticizer such as glycerin; a dihydroxy alkane such as 1,5-pentanediol as described in Milton and Murray U.S. Patent 2,960,404, issued November 15, 1960; an ester of an ethylene bis-glycolic acid such as ethylene bis(methyl glycolate) as described in Milton U.S. Patent 2,904,434, issued September 15, 1959; bis(ethoxy diethylene glycol) succinate as described in Gray U.S. Patent 2,940,854, issued June 14, 1960, or a polymeric hydrosol as results from the emulsion polymerization of a mixture of an amide of an acid of the acrylic acid series, an acrylic acid ester and a styrene-type compound as described in Tong US. Patent 2,852,386, issued September 16, 1958. The plasticizer may be added to the emulsion before or after the addition of a sensitizing dye, if used.

The emulsion can be hardened with any suitable hardener for gelatin such as formaldehyde; a halogen-substituted aliphatic acid such as mucobromic acid as described in White U.S. Patent 2,080,019, issued May 11, 1937; a compound having a plurality of acid anhydride groups such as 7,8-diphenylbicyclo(2,2,2)-7-octene- 2,3,5,6-tetracarboxylic dianhydride, or a dicarboxylic or a disulfonic acid chloride such as terephthaloyl chloride or naphthalene-1,5-disulfonyl chloride as described in Allen and Carroll U.S. Patents 2,725,294 and 2,725,295, both issued November 29, 1955; a cyclic 1,2-diketone such as cyclopentane-1,2-dione as described'in Allen and Byers U.S. Patent 2,725,305, issued November 29, 1955; a bisester of methane-sulfonic acid such as 1,2-di-(methanesulfonoxy)ethane as described in Allen and Laakso U.S. Patent 2,726,162, issued December 6, 1955; 1,3-dihydroxymethylbenzimidazol-2-one as described in July, Knott and Pollak U.S. Patent 2,732,316, issued January 24, 1956; a dialdehyde or a sodium bisulfite derivative thereof, the aldehyde groups of which are separated by 2-3 carbon atoms, such as B-methylglutaraldehyde bissodium bisulfite; a bisaziridine carboxamide such as trimethylene bis(1-aziridine carboxamide) as described in 8 Allen and Webster U.S. Patent 2,950,197, issued August 23, 1960; or 2,3-dihydroxy dioxane as described in Jeffreys U.S. Patent 2,870,013, issued January 20, 1959.

The emulsions can contain a coating aid such as sa ponin; a lauryl or oleoyl monoether of polyethylene glycol as described in Knox and Davis U.S. Patent 2,831,766, issued April 22, 1958; a salt of a sulfated and alkylated polyethylene glycol ether as described in Knox and Davis U.S. Patent 2,719,087, issued September 27, 1955; an acylated alkyl taurine such as the sodium salt of N-oleoyl- N-methyl taurine as described in Knox, Twardokus and Davis U.S. Patent 2,739,891, issued March 27, 1956; the reaction product of a dianhydride of tetracarboxybutane with an alcohol or an aliphatic amine containing from 8 to 18 carbon atoms Which is treated with a base, for example, the sodium salt of the monoester of tetracarboxybutane as described in Knox, Stenberg and \Vilson U.S. Patent 2,843,487, issued July 15, 1958; a water-soluble maleopimarate or a mixture of a water-soluble maleopimarate and a substituted glutamate salt as described in Knox and Fowler U.S. Patent 2,823,123, issued February 11, 1958; an alkali metal salt of a substituted amino acid such as disodium N-(carbo-p-tert. octylphenoxypentaethoxy)glutamate, or a sulfosuccinamate such as tetrasodium N-(1,2-dicarboxyethyl)-N-octadecyl sulfosuccinamate, or N-lauryl disodium sulfosuccinamate.

The emulsions can also be stabilized with the mercury compounds of Allen, Byers and Murray U.S. Patent 2,728,663, issued December 27, 1955; Carroll and Murray U.S. Patent 2,728,664, issued Decmeber 27, 1955; and Leubner and Murray U.S. Patent 2,728,665, issued December 27, 1955; and triazoles of Heimbach and Kelly U.S. Patent 2,444,608, issued July 6, 1948; the azindenes of Heimbach and Kelly U.S. Patents 2,444,605 and 2,444,606, issued July 6, 1948; Heimbach U.S. Patents 2,444,607, issued July 6, 1948 and 2,450,397, issued September 28, 1948; Heimbach and Clark U.S. Patent 2,444,609, issued July 6, 1948; Allen and Reynolds U.S. Patents 2,713,541, issued July 19, 1955 and 2,743,181, issued April 24, 1956; Carroll and Beach U.S. Patent 2,716,062, issued August 23, 1955; Allen and Beilfuss U.S. Patent 2,735,769, issued February 21, 1956; Reynolds and Sagal U.S. Patent 2,756,147, issued July 24, 1956; Allen and Sagura U.S. Patent 2,772,164, issued November 27, 1956, and those disclosed by Birr in Z. wiss. Phot., vol. 47, 1952, pages 2-28; the disulfides of Kodak Belgian Patent 569,317, issued July 31, 1958; the quaternary benzothiazolium compounds of Brooker and Stand U.S. Patent 2,131,038, issued September 27, 1938; the bis-quaternary salts of Allen and Wilson U.S. Patent 2,694,716, issued November 16, 1954 (e.g., decamethylene bis-benzothiazolium perchlorate etc.), and the zinc and cadmium salts of Jones U.S. Patent 2,839,405, issued June 17, 1958.

The sensitizing addenda of the invention can be used in various kinds of photographic emulsions. In addition to being useful in orthochromatic, panchromatic, and infrared sensitive emulsions, they are also useful in X-ray and other non-optically sensitized emulsions. They can be added to the emulsion before or after any optical sensitizing dyes which may be used. Various silver salts can be used as the sensitive salt such as silver bromide, silver iodide, silver chloride, or mixed silver halides such as silver chlorobr-omide or silver bromoiodide. The subject addenda can be used in emulsions intended for color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other color-generating materials, emulsions of the mixed-packet type, such as described in Godowsky U.S. Patent 2,698,794, issued January 4, 1955, or emulsions of the mixed-grain type, such as described in Carroll and Hanson U.S. Patent 2,592,243, issued April 8, 1952. Suitable color couplers usually belong to three widely known types, i.e., pyrazolone couplers, phenol couplers and open-chain ketomethylene couplers which combine with the oxidation products of aromatic primary amine silver halide developing agents to produce magenta, cyan and yellow images respectively. Development accelerators can be utilized in developing such color emulsions including polyethylene glycols, their ester derivatives, their ether derivatives typically having the formula RO(CH CH O),,H wherein R is an alkyl radical having 1 to 5 carbon atoms and wherei in n is 100, and related derivatives. The subject addenda can also be used in emulsions which form latent images predominantly on the surface of the silver halide crystal or in emulsions which form latent images predominantly inside the silve halide crystal, such as those described in Davey and Knott U.S. Patent 2,592,250, issued April 8, 1952.

The subject addenda can also be used in emulsions intended for use in dilfusion transfer processes which utilize the undeveloped silver halide in the non-image areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a receiving layer in close proximity to the original silver halide emulsion layer. Such processes are described in Rott US. Patent 2,352,014, issued June 20, 1944, and Land U.S. Patents 2,584,029, issued January 29, 1952; 2,608,236, issued December 18, 1954, and 2,543,181, issued February 27, 1951. They can also be used in color transfer processes which utilize the diffusion transfer of an imagewise distribution of developer, coupler or dye, from a light-sensitive layer to a second layer, while the two layers are in close proximity to one another. Color processes of tlu's type are described in Land U.S. Patents 2,- 599,643, issued July 10, 1951, and 2,698,798, issued Ianuary 4, 1955; Land and Rogers Belgian Patents 554,933 and 554,934, granted August 12, 1957; International Polaroid Belgian Patents 554,212, granted July 16, 1957, and 554,935, granted August 12, 1957; and Yutzy U.S. Patent 2,756,142, issued July 24, 1956.

In the preparation of the silver halide dispersions employed for preparing silver halide emulsions, there can be employed as the dispersing agent for the silver halide in its preparation, gelatin or some other colloidal material such as colloidal albumin, a cellulose derivative, or a synthetic resin, for instance, a polyvinyl compound, although gelatin is preferred. Some colloids which can be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe U.S. Patent 2,286,215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 1926% as described in U.S. Patent 2,327,808 of Lowe and Clark, issued August 24, 1943; a water-soluble ethanolamine cellulose acetate as described in Yutzy U.S. Patent 2,- 322,085, issued Ian. 15, 1943; a polyacrylamide having a combined acrylamide content of 30-60% and a specific viscosity of 0.251.5 on an imidized polyacrylamide of like acrylamide content and viscosity as described in Lowe, Minsk and Kenyon. U.S. Patent 2,541,474, issued February 13, 1951; zein as described in Lowe U.S. Patent 2,563,791, issued August 7, 1951; a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith U.S. Patent 2,768,154, issued October 23, 1956; or containing cyanoacetyl groups such as the vinyl alcohol-vinyl cyanoacetate copolymer as described in Unruh, Smith and Priest U.S. Patent 2,- 808,331, issued October 1, 1957; or a polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described in Illingsworth, Dann and Gates U.S. Patent 2,852,382, issued September 19, 1958. If desired, compatible mixtures of two or more of these colloids can be employed for dispersing the silver halide in its preparation.

The above-described emulsions of the invention can be coated on a wide variety of supports inaccordance with usual practice. Typical supports for photographic elements of the invention include cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene Addenda Addenda.

number I Po1y(thio diethylene glutarate). (M01. wt. ca. 2000). II 4-methyl-1-phenyl-3-pyrazolidone. III Hydroquinone-suliur dioxide clathrate [10.6% by weight;

S02]. Poly(2,2-thiodietl1ylsuccinate). (M01. wt. ca. 2000). P01y(gdgitydroxyethylmercaptoacetic acid). (M01. wt.

c 1,10-dithia-4,7,13,lfi-tetraoxacyclooctadecane. 1,17-di(N-ethylearbamyl)-6,12-dithia-Q-oxaheptadecane. p-Toluhydroquinoue.

Sodium bisulfite.

Sulfur dioxide.

EXAMPLE 1 Typical feature addenda of the invention were incorporated into samples of a high speed, negative-type, unoptically sensitized, gelatino-silver bromoiodide emulsion. The silver halide in the emulsion consisted of about 98% by weight of silver bromide and about 2% by weight of silver iodide. About 60 grams of gelatin per mole of silver halide was present in the emulsion. The emulsion was coated at a coverage of about 1100 mg. of silver per square foot, a cellulose acetate film support being utilized. The prepared photo-graphic elements were'then exposed in the form of film strips to kv. X-ray for 0.05 to 32 seconds through an aluminum step wedge, developed for 3 and 6 minute periods at 68 F. and then fixed, washed and driedin the usual manner. Emulsions containing none of the feature addenda were also included in the tests for purposes of comparison. The developer had essentially the following formula: v N-methyl-p-aminophenol sulfate g 2.2 Hydroquinone g 8.8 Sodium sulfite (anhydrous) g 72.0 Sodium carbonate g 130.0 Potassium bromide g 4.0

Water to make one liter.

The results of the sensit-ometric tests are summarized by the data set out in Tables A and -B below. In Tables A and B the speeds indicated are a function of the exposure necessary to give a density of .85 above background fog and expressed as a reciprocal relation to exposure, the

tained after .a 6 minute development.

Table A Concentration of addenda (grams/mole AgX) Coating Relative 'y Fog sample Compound No. speed 1 n I m When coatings (f) and (g) of Table B were developed, after the X-ray exposure, for 1.5 minutes instead of the 6 minutes, substantially the same relative speed and gamma or contrast resulted. Hence, the subject addcnda combinations not only can 'be utilized to substantially increase the speed of photographic silver halide emulsions Without an objectionable amount of accompanying fog as illustrated by the data set out in Tables A and B above, but also to substantially shorten development time.

EXAMPLE 2 Additional sensit-izer combinations of the invention were incorporated into the gelatino-silver bromoiodide described in Example 1 and coated as described in Example 1. Test samples of the prepared films were then exposed in an Eastman Ib sensitometer, developed for 3 minutes at 68 F. in the developer described in Example 1, and then fixed, washed and dried in the usual manner. The results of the sensitometric tests are summarized by the data set out in Table C below. The relative speeds are a function of the exposure necessary to give a density of 0.3 above background fog.

Table C Concentration of addenda (grams/mole AgX) Coating Relative 'y Fog sample Compound No. speed I II III IV V VI 0 0 0 O 0 100 5.50 05 2 0 0 0 0 O 191 5. 80 06 0 0 0 2 0 0 200 6. 00 08 0 O 0 0 2 0 110 5. 07 0 0 0 0 0 2 138 5.07 .17 2 1 0 0 0 0 200 5. 8O 05 2 0 10 0 0 0 219 4. 30 06 2 1 10 0 0 0 229 6. 40 06 0 O 10 2 0 0 219 5.05 07 0 0 10 0 2 0 191 6. 01 11 0 1 10 0 0 2 178 5. 09 17 With respect to the data in Table C above, Compounds II and III alone imparted substantially no speed increase to the subject emulsion.

EXAMPLE 3 The invention is further illustrated by incorporating another sensitizer combination of the invention and its components into a high speed, negative-type, unoptically sensitized, gelatino-silver bromoiodide emulsion, and thereafter coating the emulsion on a cellulose acetate film support at a coverage of about 1070 mg. of silver per 7 square foot and 595 mg. of gelatin per square foot. Test samples of the prepared films were exposed, initially and after a one week incubation at 120 F. and 50% relative humidity, in an Eastman Ib sensitometer, developed for 3 minutes at 68 F. in the developer described in Example 1, and then fixed, Washed and dried in the usual manner. The results of the sensitometric tests are summarized by the data set out in Table D below wherein the relative speeds indicated are a function of the exposure necessary to give a density of 0.3 above background fog and expressed as a reciprocal relation to exposure, the initial control speed being taken .as 100. The concentrations of addenda in Table D are represented as grams of addenda per mole of silver halide in the emulsion.

T able D Concentration of addenda (grarns/ mole AgX) Original test 1 week incubation I Coating Compound N0.

sample I 11 VIII X Rel. 'y Fog R01. 7 Fog speed speed The same results as those illustrated by the data set out in Table D above are obtained when an equivalent molar amount of sodium bisulfite (Compound IX) is substituted for the sulfur dioxide (Compound X).

EXAMPLE 4 A photographic gelatino-silver bromoiodide emulsion as described in Example 3 containing other sensitizer combinations of the invention and their components were coated on a cellulose acetate film support at a coverage of 1040 mg. of silver per square foot and 578 mg. of gelatin per square foot. The samples were exposed, initially and after a one week incubation at 120 F. and 50% relative humidity, to X-ray as described in Example 1. Portions of the coated samples were developed for 3 minutes at 68 F. in the developer described in Example 1 and then fixed washed and dried in the usual manner. Other portions of the coated samples were developed by a rapid X-ray process at a temperature of 80 F. for about 1.5 minutes, and then fixed, washed and dried, the developer having essentially the following formula:

G. N-methyl-p-aminophenol 5.0 Hydroquinone 10.0 Sodium sulfite (anhydrous) 75.0 Sodium metaborate 48.0 Sodium hydroxide 3.5 Potassium bromide 5.0 S-methyl benzotriazole 0.3 ,B-Methyl glutaraldehyde bis(sodium bisulfite) 15.0

Water to make one liter.

The results of the tests are summarized by the data set out in Table E below wherein the units are as described for the data in Table A. In Table E, the developer described in Example 1 and used in the present example is ,13- denominated Developer 1, and the developer described immediately above is denominated Developer II.

a .14 V (b) a hydroquinone silver halide developing agent and a compound capable of forming a bisulfite ion.

Table E Concentration of addenda Developer I, One week Developer II,

(grams/mole AgX) initial test incubation initial test Coating sample Compound No.

Rel. 1 Fog Rel. Fog Rel. -y Fog speed 7 speed speed I II III VII VIII IX (2.) 0 0 0 0 0 100 1. 65 08 94 1. 65 11 138 1.70 08 (b) 1 0 0 0 O 0 132 1.60 17 118 1. 60 23 191 1. 70 18 (c) 0 1 10 O 0 0 138 1. 75 03 126 1. 80 .04 331 1. 90 02 (d).. 1 1 10 0 O 0 240 1. 70 11 209 1. 80 40 1, 100 1. 85 .08 (e) 0 0 0 05 0 0 118 1. 65 .11 107 1. 70 11 166 1. 75 12 (f). 0 1 .05 0 0 182 1. 70 06 159 1. 80 07 646 1.85 06 (g) 0 0 0 0 0 0 100 1. 85 18 87 1. 90 22 129 1. 85 28 (11).. 0 0 0 03 0 0 129 1. 85 .11 112 1. 85 11 182 1. 95 12 (i) 0 1 0 0 4 1 118 1.90 .09 112 1.90 .13 251 1.80 .22 (j) 0 1 0 03 4 1 148 1.85 12 126 1. 85 14 289 2. 10

The data in Table E further illustrates the increased speeds obtained with the sensitizer combinations of the invention.

EXAMPLE 5 The hydroquinone-sulfur dioxide clathrate (Compound III) can be prepared by dissolving 110 g. of hydroquinone in 700 ml. of distilled Water at 50 C. The resulting solution is then saturated with sulfur dioxide and cooled to 5 C. A clathrate forms as yellow crystals which crystallize out of the reaction mixture and which are then filtered off and dried.

If substantial or extreme amounts of the thioether silver halide chemical sensitizer are used alone as the sensitizer in photographic silver halide emulsions to increase the speed of the emulsions, undesirable levels of fog are obtained, such being well-known to those skilled in the art. However, increased speed can be obtained in accordance with the invention, without undesirable to g, by combining relatively small amounts of thioether sensitizers with developing compositions as described and illustrated hereinabove.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected Within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer combination compris mg:

(a) a thioether silver halide chemical sensitizer,

(b) a 3-pyrazolidone silver halide developing agent,

and

(c) a hydroquinone silver halide developing agent and a compound capable of forming a bisulfite ion.

2. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer combination comprising:

(a) a thioether silver halide chemical sensitizer, and

(1)) a hydroquinone silver halide developing agent and a compound capable of forming a bisulfite ion.

3. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer combination comprismg:

(a) a polymeric thioether silver halide chemical sensitizer having the formula {-RS-} wherein R is an aliphatic radical and x is an integer of at least 3,

(b) a 3-pyrazolidone silver halide developing agent, and (c) a hydroquinone silver halide developing agent and a compound capable of forming a bisulfite ion.

4. A photographic silver halide emulsion containing a sensitizing amount of a sensitizer combination comprismg:

(a) a polymeric thioether silver halide chemical sensitizer having the formula {-RS-) wherein R is an aliphatic radical and x is an integer of at least 3, and

5. A photographic silver halide emulsion as described in claim 2 wherein the thioether chemical sensitizer has the formula wherein R is an alkylene radical having 1 to 4 carbon atoms and x is an integer of l to 10.

6. A photographic silver halide emulsion as described in claim 2 wherein the compound capable of forming a bisulfite ion is sulfur dioxide.

7. A photographic silver halide emulsion as described in claim 2 wherein the compound capable of forming a bisulfite ion is an alkali metal bisulfite.

8. A photographic gelatino-silver halide emulsion containing a sensitizer combination comprising:

(a) about .01 to 10 grams per mole of silver halide of poly(thiodiethylene glutarate) having an average molecular Weight of at least about 25 0,

(b) about .01 to 10 grams per mole of silver halide of 4-methyl-1-pl1enyl-3-pyrazolidone, and

(c) about 1 to 100 grams per mole of silver halide of hydroquinone and a minor proportionate amount of sulfur dioxide.

9. A photographic gelatino-silver halide emulsion containing a sensitizer combination comprising:

(a) about .01 to 10 grams per mole of silver halide of poly(2,2'-thiodiethyl succinate) having an average molecular Weight of at least about 250,

(b) about .01 to 10 grams per mole of silver halide of 4-methyll-phenyl-3-pyrazolidone, and

(0) about 1 to 100 grams per mole of silver halide of hydroquinone and a minor proportionate amount of sulfur dioxide.

10. A photographic gelatino-silver halide emulsion containing a sensitizer combination comprising:

(a) about .01 to 10 grams per mole of silver halide of poly(flahydroxyethylmercapto acetic acid) having an average molecular Weight of at least about 250,

(b) about .01 to 10 grams per mole of silver halide of 4-methyl-l-phenyl-3-pyrazolidone, and

(c) about 1 to 100 grams per mole of silver halide of hydroquinone and a minor proportionate amount of sulfur dioxide.

11. A photographic gelatino-silver halide emulsion containing a sensitizer combination comprising:

(a) about .01 to 10 grams per mole of silver halide of 1,10-di-thio-4,7,13,16-tetraox-acycloocta decane,

(b) about .01 to 10 grams per mole of silver halide of 4-methyl-l-phenyl-3-pyrazolidone, and

(c) about 1 to 100 grams per mole of silver halide of hydroquinone and a minor proportionate amount of sulfur dioxide.

12. A photographic gelatino-silver halide emulsion containing a sensitizer combination comprising:

(a) about .01 to 10 grams per mole of silver halide of 1,17-di(N-ethylcarbamyl)6,12 dithia-9 oxaheptadecane,

(b) about .01 to 10 grams per mole of silver halide of 4-methyl-1-phenyl-3-pyrazolidone, and

(0) about 1 to 100 grams per mole of silver halide of p toluhydroquinone and a minor proportionate amount of sodium bisulfite.

13. A photographic silver halide emulsion as described in claim 2 wherein the thioether silver halide chemical sensitizer is selected from the group consisting of poly (thiodiethylene glutarate), poly(2,2' thiodiethyl succinate), poly(/B-hydroxyethylmercapto acetic acid), 1,10- dithia-4,7,l3,16tetraoxacycloocta decane, and 1,l7-di(N- ethylcarbamyl)-6,12-dithia-9-oxaheptadecane.

5 thereon a photographic silver halide emulsion as described in claim 2.

References Cited by the Examiner UNITED STATES PATENTS 7/62 Graham et a1 9666 FOREIGN PATENTS 845,928 8/60 GreatBritain.

0 NORMAN G. TORCHIN, Primary Examiner. 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION CONTAINING A SENSITIZING AMOUNT OF A SENSITIZER COMBINATION COMPRISING: (A) A THIOETHER SILVER HALIDE CHEMICAL SENSITIZER, (B) A 3-PYRAZOLIDONE SILVER HALIDE DEVELOPING AGENT, AND (C) A HYDROQUINONE SILVER HALIDE DEVELOPING AGENT AND A COMPOUND CAPABLE OF FORMING A BISULFITE ION. 